Cocaine-induced cerebral vasoconstriction differs as a function of sex and menstrual cycle phase

Effects of long-term cocaine self-administration on brain resting-state functional connectivity in nonhuman primates

Long-term cocaine use is associated with a variety of neural and behavioral deficits that impact daily function. This study was conducted to examine the effects of chronic cocaine self-administration on resting-state functional connectivity of the dorsal anterior cingulate (dACC) and putamen-two brain regions involved in cognitive function and motoric behavior-identified in a whole brain analysis. Six adult male squirrel monkeys self-administered cocaine (0.32 mg/kg/inj) over 140 sessions. Six additional monkeys that had not received any drug treatment for ~1.5 years served as drug-free controls. Resting-state fMRI imaging sessions at 9.4 Tesla were conducted under isoflurane anesthesia. Functional connectivity maps were derived using seed regions placed in the left dACC or putamen. Results show that cocaine maintained robust self-administration with an average total intake of 367 mg/kg (range: 299-424 mg/kg). In the cocaine group, functional connectivity between the dACC seed and regions primarily involved in motoric behavior was weaker, whereas connectivity between the dACC seed and areas implicated in reward and cognitive processing was stronger. In the putamen seed, weaker widespread connectivity was found between the putamen and other motor regions as well as with prefrontal areas that regulate higher-order executive function; stronger connectivity was found with reward-related regions. dACC connectivity was associated with total cocaine intake. These data indicate that functional connectivity between regions involved in motor, reward, and cognitive processing differed between subjects with recent histories of cocaine self-administration and controls; in dACC, connectivity appears to be related to cumulative cocaine dosage during chronic exposure.

Cocaine differentially affects synaptic activity in memory and midbrain areas of female and male rats: an in vivo MEMRI study

Manganese enhanced magnetic resonance imaging (MEMRI) has been previously used to determine the effect of acute cocaine on calcium-dependent synaptic activity in male rats. However, there have been no MEMRI studies examining sex differences in the functional neural circuits affected by repeated cocaine. In the present study, we used MEMRI to investigate the effects of repeated cocaine on brain activation in female and male rats. Adult female and male rats were scanned at 4.7 Tesla three days after final treatment with saline, a single cocaine injection (15 mg kg^-1, i.p. × 1 day) or repeated cocaine injections (15 mg kg^-1, i.p. × 10 days). A day before imaging rats were provided with an i.p. injection of manganese chloride (70 mg kg^-1). Cocaine produced effects on MEMRI activity that were dependent on sex. In females, we observed that a single cocaine injection reduced MEMRI activity in hippocampal CA3, ventral tegmental area (VTA), and median Raphé, whereas repeated cocaine increased MEMRI activity in dentate gyrus and interpeduncular nucleus. In males, repeated cocaine reduced MEMRI activity in VTA. Overall, it appeared that female rats showed a general trend towards increase MEMRI activity with single cocaine and reduced activity with repeated exposure, while male rats showed a trend towards opposite effects. Our results provide evidence for sex differences in the in vivo neural response to cocaine, which involves primarily hippocampal, amygdala and midbrain areas.

Sex-Specific Characteristics of the Microcirculation

The requirements of metabolizing tissue are both continuous and variable; accordingly, the microvasculature serving that tissue must be similarly dynamic. Just as it is recognized that males and females of the same species have differing metabolic requirements, is it not likely that the microvasculature serving these tissues will differ by sex? This section focusing on the constituents of the microcirculation identifies what is known presently about the role sex plays in matching metabolic demand with microvascular function and areas requiring additional study. Many of the identified sex differences are subtle and easily ignored. In the aggregate, though, they can profoundly alter phenotype, especially under stressful conditions including pregnancy, exercise, and disease states ranging from diabetes to heart failure. Although the features presently identified to "have sex" range from differences in growth, morphology, protein expression, and intracellular signaling, males and females alike achieve homeostasis, likely by different means. Studies of microvascular sexual dimorphism are also identifying age as an independent but interacting factor requiring additional attention. Overall, attempting to ignore either sex and/or age is inappropriate and will prevent the design and implementation of appropriate interventions to present, ameliorate, or correct microvascular dysfunction.

Cocaine and methamphetamine induce opposing changes in BOLD signal response in rats

BACKGROUND

Neuroimaging studies in psychostimulant addicts have reported functional neural activity changes in brain regions involved in relapse. However, the difference between the effects of the psychostimulants methamphetamine and cocaine on neuronal activity in a similar setting not been clarified. Since studies in humans are limited by the inability to study the initial impact of psychostimulant drugs, we addressed this issue in a rat model.

OBJECTIVE

Here, we report methamphetamine and cocaine-induced blood-oxygen-level dependent (BOLD) signal change using functional magnetic resonance imaging (fMRI) in rats receiving drug for the first time during the imaging session.

METHODS

Twenty-three male Long Evans rats underwent fMRI imaging and received an intravenous infusion of methamphetamine, cocaine, or saline. Anatomical and pharmacological fMRI (pfMRI) were performed on a 7T BioSpec dedicated research MR scanner under isoflurane gas (1.5-2%). After collecting baseline data for 10min, rats received drug over the next 10min for a total 40min scan time. Data were then preprocessed and statistically analyzed in anatomically defined regions of interest (ROIs) that have been implicated in persistent drug seeking and relapse.

RESULTS

Methamphetamine during the imaging session resulted in a sustained negative BOLD signal change in key regions of the relapse circuit, except for the prefrontal cortex. In contrast, cocaine evoked a positive or unchanged BOLD signal in these same regions. In all of the investigated ROIs, there were no changes in BOLD signal following saline.

CONCLUSION

Acute methamphetamine and cocaine have distinct patterns of functional activity as measured by pfMRI.

New perspectives on using brain imaging to study CNS stimulants

While the recent application of brain imaging to study CNS stimulants has offered new insights into the fundamental factors that contribute to their use and abuse, many gaps remain. Brain circuits that mediate pleasure, dependence, craving and relapse are anatomically, neurophysiologically and neurochemically distinct from one another, which has guided the search for correlates of stimulant-seeking and taking behavior. However, unlike other drugs of abuse, metrics for tolerance and physical dependence on stimulants are not obvious. The dopamine theory of stimulant abuse does not sufficiently explain this disorder as serotonergic, GABAergic and glutamagergic circuits are clearly involved in stimulant pharmacology and so tracking the source of the "addictive" processes must adopt a more multimodal, multidisciplinary approach. To this end, both anatomical and functional magnetic resonance imaging (MRI), MR spectroscopy (MRS) and positron emission tomography (PET) are complementary and have equally contributed to our understanding of how stimulants affect the brain and behavior. New vistas in this area include nanotechnology approaches to deliver small molecules to receptors and use MRI to resolve receptor dynamics. Anatomical and blood flow imaging has yielded data showing that cognitive enhancers might be useful adjuncts in treating CNS stimulant dependence, while MRS has opened opportunities to examine the brain's readiness to accept treatment as GABA tone normalizes after detoxification. A desired outcome of the above approaches is being able to offer evidence-based rationales for treatment approaches that can be implemented in a more broad geographic area, where access to brain imaging facilities may be limited. This article is part of the Special Issue entitled 'CNS Stimulants'.

Antiandrogen pretreatment alters cocaine pharmacokinetics in men

Among cocaine users, men experience more adverse brain and vascular effects than their female counterparts. This could be caused by testosterone, which may potentiate some of cocaine's effects. We examined whether antiandrogen (flutamide, FL) pretreatment alters cocaine's acute behavioral, physiologic, and pharmacokinetic effects in men with histories of occasional cocaine use. Participants (N = 8) were pretreated with oral FL (250 mg) and placebo on separate study days followed by intravenous (IV) cocaine (0.4 mg/kg). Vital signs, subjective ratings, and blood samples for cocaine and metabolites were obtained at baseline and for 90 minutes after cocaine administration. FL, itself, had no effects on physiologic or subjective responses; however, after cocaine, heart rate recovered faster with FL pretreatment. Flutamide reduced peak plasma cocaine levels (Wilcoxon signed-rank z = 2.1, P < 0.04) and area under the curve (AUC; z = 1.96, P < 0.05). Additionally, FL reduced EME levels (z = 1.96, P < 0.05) and AUC for BE and EME (z = 2.38, P < 0.02 and z = 1.96, P < 0.05, respectively). These results suggest that FL may alter cocaine pharmacokinetics in men. Because cocaine and BE are vasoconstrictive, the data imply that FL might reduce some of cocaine's cardiovascular effects.

Contributions of neuroimaging to understanding sex differences in cocaine abuse

A consistent observation in drug abuse research is that males and females show differences in their response to drugs of abuse. In order to understand the neurobiology underlying cocaine abuse and effective treatments, it is important to consider the role of sex differences. Sex hormones have been investigated in both behavioral and molecular studies, but further evidence addressing drug abuse and dependence in both sexes would expand our knowledge of sex differences in response to drugs of abuse. Neuroimaging is a powerful tool that can offer insight into the biological bases of these differences and meet the challenges of directly examining drug-induced changes in brain function. As such, neuroimaging has drawn much interest in recent years. Specifically, positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) technology have emerged as effective noninvasive approaches for human and animal models. Studies have revealed sex-specific changes in patterns of brain activity in response to acute cocaine injection and after prolonged cocaine use. SPECT and PET studies have demonstrated changes in the dopamine transporter but are less clear on other components of the dopaminergic system. This review highlights contributions of neuroimaging toward understanding the role of sex differences in the drug abuse field, specifically regarding cocaine, and identifies relevant questions that neuroimaging can effectively address.

Estradiol: a key biological substrate mediating the response to cocaine in female rats

A consistent finding in drug abuse research is that males and females show differences in their response to drugs of abuse. In women, increased plasma estradiol is associated with increased vulnerability to the psychostimulant and reinforcing effects of drugs of abuse. Our laboratory has focused on the role of estradiol in modulating the response to cocaine. We have seen that ovariectomy increases the locomotor response to a single cocaine injection, whereas estradiol exacerbates the locomotor response to repeated cocaine administration. Cocaine-induced sensitization of brain activity, as measured by fMRI, is also dependent on plasma estradiol. Moreover, we observed that although all ovariectomized rats show conditioned place preference to cocaine, it is more robust in ovariectomized rats with estradiol. Opioid receptors are enriched in brain regions associated with pleasure and reward. We find that in females, the effectiveness of kappa opioid agonists in decreasing the locomotor response to repeated cocaine varies with plasma estradiol. We also find that estradiol regulates the density of mu opioid receptors in brains areas associated with reward. These data hint that in females, estradiol modulates the behavioral effects of cocaine by regulating mu and kappa opioid signaling in mesocorticolimbic brain structures. Identifying the mechanisms that mediate differences in vulnerability to drugs of abuse may lead to effective therapeutic strategies for the treatment and prevention of addiction and relapse. We encourage health practitioners treating persons addicted to drugs to consider gender differences in response to particular pharmacotherapies, as well the sex steroid milieu of the patient.

Neurochemistry of drug action: insights from proton magnetic resonance spectroscopic imaging and their relevance to addiction

Proton magnetic resonance spectroscopy ((1)H MRS) is a noninvasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, (1)H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis of psychiatric disorders. As of relatively recently, (1)H MRS has found its way into substance abuse research, and it is beginning to become recognized as a valuable complement in the brain imaging toolbox that also contains positron emission tomography, single-photon-emission computed tomography, and functional magnetic resonance imaging. Drug abuse studies using (1)H MRS have identified several biochemical changes in the brain. The most consistent alterations across drug class were reductions in N-acetylaspartate and elevations in myo-inositol, whereas changes in choline, creatine, and amino acid transmitters also were abundant. Together, the studies discussed herein provide evidence that drugs of abuse may have a profound effect on neuronal health, energy metabolism and maintenance, inflammatory processes, cell membrane turnover, and neurotransmission, and these biochemical changes may underlie the neuropathology within brain tissue that subsequently gives rise to the cognitive and behavioral impairments associated with drug addiction.

Low doses of cocaine decrease, and high doses increase, anxiety-like behavior and brain progestogen levels among intact rats

There are sex and hormonal differences in response to cocaine that have been demonstrated in people and animal models. Cocaine can alter secretion of progestogens, such as progesterone (P), and its neuroactive metabolite, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP). However, little research has been done on the neuroendocrine effects in the initiation phase of cocaine use. We hypothesize that some sex/hormonal differences in initiation phase responses to cocaine may be related to formation of progestogens. To investigate the role of progestogens in sex differences in response to acute cocaine, male and female rats in the high (proestrous) or low (diestrous) progestogen phase of the estrous cycle were administered cocaine (0, 5, 10, or 20mg/kg, IP). We examined cocaine's acute neuroendocrine effects on P and 3alpha,5alpha-THP levels, as well as its effects on acute psychomotor stimulation, anxiety, and sexual behaviors. Among rats that had P and/or 3alpha,5alpha-THP levels increased in response to cocaine, enhanced acute psychomotor stimulation was observed. Results suggest that cocaine produces U-shaped curves for progestogens, and anxiety-like behaviors. Male rats were less susceptible to these effects of cocaine than were proestrous or diestrous female rats. However, cocaine's disruption of sexual behaviors was similar among males and proestrous females. These data suggest a complex interaction between hormonal milieu and the neuroendocrine and behavioral effects of cocaine.

Perfusion magnetic resonance imaging in psychiatry

INTRODUCTION

Cerebral perfusion imaging using magnetic resonance imaging (MRI) is widely used in the research and clinical fields to assess the profound changes in blood flow related to ischemic events such as acute stroke, chronic steno-occlusive disease, vasospasm, and abnormal vessel formations from congenital conditions or tumoral neovascularity. With continuing improvements in the precision of MRI-based perfusion techniques, it is increasingly feasible to use this tool in the study of the subtle brain perfusion changes occurring in psychiatric illnesses. This article aims to review the existing literature on applications of perfusion MRI in psychiatric disorder and substance abuse research. The article also provides a brief introductory overview of dynamic susceptibility contrast MRI and arterial spin labeling techniques. An outlook of necessary steps to bring perfusion MRI into the realm of clinical psychiatry as a diagnostic tool is brought forth. Opportunities for research in unexplored disorders and with higher field strengths are briefly examined.

METHODS

PubMed, ISI Web of Knowledge & Scopus were used to search the literature and cross reference several neuropsychiatric disorders with a search term construct, including "magnetic resonance imaging," "dynamic susceptibility contrast," "arterial spin labeling," perfusion or "cerebral blood flow" or "cerebral blood volume" or "mean transit time." The list of disorders used in the search included schizophrenia, depression and bipolar disorder, dementia and Alzheimer's disease, Parkinson's disease, posttraumatic stress disorder, autism, Asperger disease, attention deficit, Tourette syndrome, obsessive-compulsive disorder, Huntington's disease, bulimia nervosa, anorexia nervosa, and substance abuse. For each disorder for which perfusion MRI studies were found, a brief overview of the disorder symptoms, treatment, prevalence, and existing models is provided, and previous findings from nuclear medicine-based perfusion imaging are overviewed. Findings of perfusion MRI studies are then summarized, and overlap of findings are discussed. Overarching conclusions are made, or an outlook for future work in the area is offered, where appropriate.

RESULTS

Despite the now fairly broad availability of perfusion MRI, only a limited number of studies were found using this technology. The search produced 13 studies of schizophrenia, 7 studies in major depression, 12 studies in Alzheimer's disease, and 2 studies in Parkinson's disease. Drug abuse and other disorders have mainly been studied with nuclear medicine-based perfusion imaging. The literature concerning the use of perfusion imaging in psychiatry has not been reviewed in the last 5 years or more. The use of MRI for perfusion measurements in psychiatry has not been reviewed in 10 years.

CONCLUSIONS

Although MRI-based perfusion imaging in psychiatry has mainly been used as a research tool, a path is progressively being cleared for its application in clinical diagnostic and treatment monitoring. The precision of perfusion MRI methods now rivals that of nuclear medicine-based perfusion imaging techniques. Because of their noninvasive nature, arterial spin labeling methods have gained popularity in studies of neuropsychiatric disorders such as schizophrenia, depression, Alzheimer's, and Parkinson's diseases. Perfusion imaging measurements have yet to be included within the diagnostic criteria of neuropsychiatric disorders despite having shown to have great discriminant power in specific disorders. As this young methodology continues to improve and research studies demonstrate the correlation of measured perfusion abnormalities to microcirculatory abnormalities and neuropsychiatric symptomatology, the idea of including such a test within diagnostic criteria for certain mental illnesses becomes increasingly plausible.

Children's cognitive ability from 4 to 9 years old as a function of prenatal cocaine exposure, environmental risk, and maternal verbal intelligence

This study examined the effects of prenatal cocaine exposure, environmental risk, and maternal verbal intelligence on children's cognitive ability. Gender and age were examined as moderators of potential cocaine exposure effects. The Stanford-Binet IV intelligence test was administered to 231 children (91 cocaine exposed, 140 unexposed) at ages 4, 6, and 9 years. Neonatal medical risk and other prenatal exposures (alcohol, cigarettes, and marijuana) were also examined for their unique effects on child IQ. Mixed models analysis indicated that prenatal cocaine exposure interacted with gender, as cocaine-exposed boys had lower composite IQ scores. Age at assessment did not moderate this relation, indicating that cocaine-exposed boys had lower IQs across this age period. A stimulating home environment and high maternal verbal IQ also predicted higher composite IQ scores. Cocaine-exposed boys had lower scores on the Abstract/Visual Reasoning subscale, with trends for lower scores on the Short-Term Memory and Verbal Reasoning subscales, as exposure effects were observed across domains. The findings indicate that cocaine exposure continues to place children at risk for mild cognitive deficits into preadolescence. Possible mechanisms for the Exposure x Gender interaction are discussed.

Menstrual cycle phase and responses to drugs of abuse in humans

Researchers have recently become aware of the importance of including women in research, including drug abuse research. With this increased awareness has come an increased scientific interest in the potential influence of menstrual cycle phase on responses to drugs. In this review, we discuss recent studies that have examined subjective and physiological responses to drugs of abuse in relation to menstrual cycle phase. With most of the drugs reviewed, including alcohol, benzodiazepines, caffeine, marijuana, nicotine and opioids, responses to the drugs were not different were inconsistent across cycle phases. However, with psychomotor stimulant drugs, such as amphetamine and cocaine, responses to the drugs were greater during the follicular, compared to the luteal, phase of the cycle. These findings suggest that, consistent with certain pre-clinical findings, circulating levels of ovarian hormones influence the central effects of stimulant drugs in women. With other drugs, the evidence to date suggests that ovarian hormones have modest, if any, effects on responses to abused drugs. We discuss methodological issues relating to inclusion of women with regular menstrual cycles.

Sex differences in medial and lateral orbitofrontal cortex hypoperfusion in cocaine-dependent men and women

BACKGROUND

The different clinical trajectories of cocaine-dependent men and women may be a consequence of distinct neurobiological substrates. Hypoperfusion of the orbitofrontal cortex (OFC) has previously been reported in individuals addicted to cocaine and has been posited as a biological mediator of relapse due to impulsivity or impaired decision making.

OBJECTIVE

This study assessed regional cerebral blood flow (rCBF) between abstinent cocaine-dependent men and women and sex-matched healthy controls.

METHODS

Cocaine-dependent subjects were abstinent from cocaine for 11 to 28 days and had no other major mental health or substance use disorders. rCBF was assessed with single photon emission computed tomography after administration of a placebo saline infusion. A resting scan was also obtained in a subset of cocaine-dependent and control men.

RESULTS

In the 35 cocaine-dependent and 37 healthy control subjects examined, a sex-by-group effect was observed for the left lateral (P=0.001), right lateral (P=0.002), and medial (P<0.02) OFC. Cocaine-dependent men demonstrated significantly lower right and left lateral, but not medial, OFC rCBF compared with sex-matched healthy controls after placebo infusion (P<or=0.001). Similar bilateral OFC decreases were observed in male cocaine-dependent subjects at rest. In contrast, cocaine-dependent women showed lower rCBF in the medial, but not lateral, OFC relative to sex-matched healthy controls after placebo infusion (P<0.01). Male cocaine-dependent subjects also showed decreased rCBF (P<0.01) in the bilateral anterolateral temporal cortex and anterior cingulate, whereas decreased rCBF was observed in female cocaine-dependent subjects in the bilateral superior frontal gyri. Large and diffuse areas of increased rCBF were observed after placebo infusion in cocaine-dependent men, but not in women, relative to sex-matched healthy controls.

CONCLUSIONS

rCBF appears to be reduced in the bilateral OFC in cocaine-dependent men and in the medial OFC in cocaine-dependent women. Sex differences in the medial and lateral OFC rCBF may be relevant to understanding relapse characteristics differentiating men and women addicted to cocaine.

Why sex matters for neuroscience

A rapidly burgeoning literature documents copious sex influences on brain anatomy, chemistry and function. This article highlights some of the more intriguing recent discoveries and their implications. Consideration of the effects of sex can help to explain seemingly contradictory findings. Research into sex influences is mandatory to fully understand a host of brain disorders with sex differences in their incidence and/or nature. The striking quantity and diversity of sex-related influences on brain function indicate that the still widespread assumption that sex influences are negligible cannot be justified, and probably retards progress in our field.

Hemodynamic and metabolic changes induced by cocaine in anesthetized rat observed with multimodal functional MRI

RATIONALE

Physiological changes (such as heart rate and respiration rate) associated with strong pharmacological stimuli could change the blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) mapping signals, independent of neural activity.

OBJECTIVES

This study investigates whether the physiological changes per se associated with systemic cocaine administration (1 mg/kg) contaminate the BOLD fMRI signals by measuring BOLD and cerebral blood flow (CBF) fMRI and estimating the cerebral metabolic rate of oxygen (CMRO(2)) changes.

MATERIALS AND METHODS

BOLD and CBF fMRI was performed, and changes in CMRO(2) were estimated using the BOLD biophysical model.

RESULTS

After systemic cocaine administration, blood pressure, heart rate, and respiration rate increased, fMRI signals remained elevated after physiological parameters had returned to baseline. Cocaine induced changes in the BOLD signal within regions of the reward pathway that were heterogeneous and ranged from -1.2 to 5.4%, and negative changes in BOLD were observed along the cortical surface. Changes in CBF and estimated CMRO(2) were heterogeneous and positive throughout the brain, ranging from 14 to 150% and 10 to 55%, respectively.

CONCLUSIONS

This study demonstrates a valuable tool to investigate the physiological and biophysical basis of drug action on the central nervous system, offering the means to distinguish the physiological from neural sources of the BOLD fMRI signal.

Profile of executive and memory function associated with amphetamine and opiate dependence

Cognitive function was assessed in chronic drug users on neurocognitive measures of executive and memory function. Current amphetamine users were contrasted with current opiate users, and these two groups were compared with former users of these substances (abstinent for at least one year). Four groups of participants were recruited: amphetamine-dependent individuals, opiate-dependent individuals, former users of amphetamines, and/or opiates and healthy non-drug taking controls. Participants were administered the Tower of London (TOL) planning task and the 3D-IDED attentional set-shifting task to assess executive function, and Paired Associates Learning and Delayed Pattern Recognition Memory tasks to assess visual memory function. The three groups of substance users showed significant impairments on TOL planning, Pattern Recognition Memory and Paired Associates Learning. Current amphetamine users displayed a greater degree of impairment than current opiate users. Consistent with previous research showing that healthy men are performing better on visuo-spatial tests than women, our male controls remembered significantly more paired associates than their female counterparts. This relationship was reversed in drug users. While performance of female drug users was normal, male drug users showed significant impairment compared to both their female counterparts and male controls. There was no difference in performance between current and former drug users. Neither years of drug abuse nor years of drug abstinence were associated with performance. Chronic drug users display pronounced neuropsychological impairment in the domains of executive and memory function. Impairment persists after several years of drug abstinence and may reflect neuropathology in frontal and temporal cortices.

Cerebral blood flow velocity and erythrocyte deformability in heavy alcohol drinkers at the acute stage and two weeks after withdrawal

OBJECTIVE

The aim of the study was to measure changes in blood flow velocity (V(mean)) and erythrocyte deformability (ED) in heavy alcohol drinkers after withdrawal and the relationship between them.

METHODS

The subjects were 32 heavy alcohol drinkers, mean age 47 years (22 men and 10 women). V(mean) was determined by a transcranial 2 MHz pulsed Doppler probe. ED was estimated by the method of cation-osmotic haemolysis (COH). The results were compared with those for 20 healthy volunteers.

RESULTS

The study revealed a significant decrease in V(mean) and ED after admission. V(mean) in the left middle cerebral artery (MCA) was 45.1+/-10.2 cm/s as compared with 59.1+/-7.5 cm/s in controls; in the right MCA, it was 46.8+/-11.3 cm/s as compared with 59.0+/-7.6 cm/s in controls (p < 0.001 in each case). But while V(mean) was significantly increased after 14 days withdrawal (54.4+/-10.4 cm/s in the left MCA, p < 0.001, and 54.3+/-12.1 cm/s in the right MCA, p < 0.01), ED showed only small change. A significant difference between V(mean) in men and women was found.

CONCLUSION

The changes in V(mean) after withdrawal are more influenced by plasma composition than by changes in ED.

Neuroimaging study of sex differences in the neuropathology of cocaine abuse

BACKGROUND

Female and male substance abusers differ in their disease patterns and clinical outcomes. An important question in addiction neuroscience thus concerns the neural substrates underlying these sex differences.

OBJECTIVE

This article aims to examine what is known of the neural mechanisms involved in the sex differences between substance abusers.

METHODS

We reviewed neuroimaging studies that addressed sex differences in cerebral perfusion deficits after chronic cocaine use and in regional brain activation during pharmacologic challenge and cue-induced craving. We also present results from a preliminary study in which cocaine-dependent men and women participated in script-guided imagery of stress- and drug cue-related situations while blood oxygenation level-dependent signals of their brain were acquired in a 1.5T scanner. Spatial pre-processing and statistical analysis of brain images were performed. Regional brain activation was compared between stress and drug cue trials in men versus women.

RESULTS

The results of our study showed greater activation in the left uncus and right claustrum (both, statistical threshold of P = 0.01, uncorrected; extent = 10 voxels) in men (n = 5) during drug cue trials compared with stress trials. No brain regions showed greater activation during stress trials compared with drug cue trials. In contrast, women (n = 6) showed greater activation in the right medial and superior frontal gyri during stress trials compared with drug cue trials at the same statistical threshold. No brain regions showed more activation during drug cue trials than during stress trials.

CONCLUSIONS

The studies reviewed underscore the need to consider sex-related factors in examining the neuropathology of cocaine addiction. Our preliminary results also suggest important sex differences in the effect of stress- and drug cue-associated brain activation in individuals with cocaine use disorder.

Addiction – who is not affected?

Addiction and addiction-related behaviour increased during the past decades. Several substances with psychoactive attributes, like opioids, cocaine or alcohol, can lead to dependence with physical and/or mental symptoms. In addition to substance-related addiction, non-substance-related dependence requires special attention. Increasing numbers of workaholics and patients suffering from internet-addiction, gambling or eating-disorders can be observed. To meet international treatment standards for addiction, diversification of therapy is necessary and, additionally, gender-related aspects in development and treatment of dependence and addiction-related behaviour are essential for state-of-the-art therapy of this patient population.

Preliminary evidence of the cardiovascular effects of polysubstance misuse in nightclubs

Adverse reactions to polysubstance misuse are common in nightclubs, yet little is known of the physiological effects of polysubstance misuse in this environment. This study examined the heart rate, blood pressure and oral temperature of 50 participants recruited in a nightclub on four separate nights. In addition, the increase in environmental temperature was recorded throughout each night. There were no differences in oral temperature between polysubstance misusers (i.e. those who used Ecstasy, amphetamine, cocaine, alcohol and cannabis) and alcohol/cannabis misusers. On the other hand, there were significant differences in both heart rate and blood pressure between the two groups. These data suggest that polysubstance misusers may be at risk from cardio- and cerebrovascular toxicity. Further field/on-site work is clearly needed to investigate the effects of polysubstance misuse.

Brain T2 relaxation times correlate with regional cerebral blood volume

We previously reported cerebellar and putaminal transverse relaxation time (T2) differences in children with ADHD and in adults with childhood trauma. As brain T2 can be altered by deoxyhemoglobin concentration ([dHb]) and because [dHb] is proportional to regional cerebral blood volume (rCBV), at steady state we attributed those differences to rCBV changes. Studies in other species have established a correlation between T2 and rCBV; however this has yet to be demonstrated in human brain. Echo planar imaging (EPI) T2 relaxometry and dynamic susceptibility-contrast (DSC) MRI were used to measure T2 and rCBV in 11 healthy adults. Significant T2-rCBV correlations were observed in both cerebellar vermis and putamen (r = 0.759,p = 0.007;r = 0.782,p = 0.004, respectively). These correlations predict 9 +/- 3% and 10 +/- 3% rCBV changes, respectively, for each 1-msec change in T2. Consequently, brain T2 measurements may be useful for estimating steady-state rCBV.

White matter hyperintensities in subjects with cocaine and opiate dependence and healthy comparison subjects

The prevalence, severity, and location of white matter signal hyperintensities (WMH) on brain magnetic resonance images were compared in patients with cocaine or opiate dependence and healthy subjects. Patients with cocaine (n=32) and opiate dependence (n=32), whose diagnoses were confirmed with the Structured Clinical Interview for DSM-IV, and age- and sex-matched healthy subjects (n=32) were scanned using a 1.5 T whole body GE magnetic resonance scanner. Axial proton-density and T2-weighted images were obtained as well as fluid-attenuated inversion recovery axial images. The severity of WMH was assessed separately for deep (and insular) and periventricular WMH, using a modified composite version of the rating scales of Fazekas and Coffey. The cocaine-dependent group had greater severity of WMH than the opiate-dependent group, which in turn had greater severity of WMH than the healthy comparison group (odds ratios=2.54 and 2.90, respectively). The cocaine-dependent group had greater lesion severity of deep and insular WMH than the opiate-dependent group and the healthy comparison group (odds ratio>3.25 for deep WMH; odds ratio>4.38 for insular WMH). For periventricular WMH, there were no significant differences between the three groups. The frontal lobes were the predominant locations of WMH in both substance-dependent groups. The greater prevalence and severity of WMH in cocaine-dependent subjects than in opiate-dependent subjects may reflect the fact that cocaine induces more ischemia via vasoconstriction than opiates. Also, there was a trend for lower WMH severity in substance-dependent women relative to the healthy comparison group, possibly due to estrogen's protective effect against cerebrovascular accidents.

Gender differences in self-reported anxiety, depression, and somatization among ecstasy/MDMA polydrug users, alcohol/tobacco users, and nondrug users

Previous research has found gender differences in both psychological and physiological responses to drugs. The present investigation explores gender variability in patterns of drug use in relation to self-reported depression, anxiety, and somatization. The current study confirms that heavy illegal drug users are represented by a preponderance of males than females. However, within each drug group category, females generally reported higher psychopathology scores than males. This was significant for all three subscales in the alcohol/tobacco group, for depression scores in the alcohol/tobacco, cannabis/alcohol, and light Ecstasy users group, and for depression scores for the alcohol group. Interestingly, in the male sample, drug users reported higher symptom ratings than nondrug users, whereas women's scores remained constant across drug groups.

The expanding effects of cocaine: studies in a nonhuman primate model of cocaine self-administration

Although neuroimaging investigations in human cocaine abusers have provided important insights into the brain changes that accompany drug use, the interpretation of reports in human abusers can be very difficult. Studies in nonhuman primates provide a way to systematically evaluate the structural and functional adaptations engendered by cocaine self-administration without the confounds of human research. Functional activity, measured with metabolic mapping methods, and markers of the dopamine system, assessed autoradiographically, were evaluated over the course of chronic cocaine self-administration (5 days, 3.3 months, and 15-22 months). Within the striatum the topography of these responses shifts dramatically over time. Changes in functional activity and alterations in the dopamine system occupy larger and larger portions of dorsal and ventral striatum with increasing durations of cocaine exposure. The growing impact of cocaine suggests that the elements of the behavioral repertoire outside of the influence of cocaine become smaller and smaller with increasing durations of exposure to drug use resulting in cocaine's dominance over all aspects of the addict's life.

Epidemiology of substance use disorders in women

Significant gender differences exist in the prevalence of substance use disorders in the United States. There is a trend among boys and girls aged 12 to 17 years toward comparable rates of use and initiation for alcohol, cocaine, heroin, and tobacco. If this trend continues, over time there may be a narrowing of the male-to-female prevalence ratios of substance abuse in the older age groups. This possibility is particularly disturbing because women have a heightened vulnerability to medical, physical, mental, and social consequences of substance use. Women also carry additional unique risks during pregnancy because of the effect on neonates. In addition, they have certain gender-specific cancer risks. Given this and the declining age of initiation of substance use in women, prevention and treatment efforts especially geared toward women (eg, education of all medical and paramedical staff, screening in primary care clinics, detection of drug use early in pregnancy or before conception, brief interventions and treatment programs that integrate women's needs) are exceedingly important to stop and ultimately reverse this growing trend.

Impaired Decision Making Related to Working Memory Deficits in Individuals With Substance Addictions

This study examined whether individuals with substance dependence (ISDs) show impairments in working memory and whether there is a relationship between their impairments in decision making as measured by the gambling task (GT) paradigm and working memory as measured by a delayed nonmatching to sample (DNMS) task. Using the GT, 11% of healthy control participants and 61% of ISDs opted for choices with high immediate gains in spite of higher future losses. For the ISDs and controls with equal GT impairments, the ISDs performed significantly lower than controls on the DNMS task. The nonimpaired ISDs on the GT also performed significantly worse than matched controls on the DNMS task. The DNMS task deficit in ISDs was across all delay times, suggesting the deficit may lie in the "executive" process of working memory, which supports earlier findings (E. M. Martin et al., 2003). The authors suggest that the prefrontal cortex hosts multiple distinct mechanisms of decision making and inhibitory control and that ISDs may be affected in any one or combination of them.